Scroll type compressor and method of making the same

ABSTRACT

A scroll type compressor has a housing, a fixed scroll member fixed to the housing, a drive shaft rotatably supported by the housing, a movable scroll member accommodated in the housing, an inlet formed through the housing and a discharge device provided for one of the movable. scroll member and the fixed scroll member. The movable scroll member faces the fixed scroll member. The movable scroll member and the fixed scroll member define a compression region. Gas introduced into the compressor via the inlet is compressed in the compression region by orbiting the movable scroll member relative to the fixed scroll member by rotation of the drive shaft, and is discharged via the discharge device. A plane bearing is disposed between the drive shaft and the housing to at least partially seal any gap between the drive shaft and the housing against the passage of the pressurized gas therethrough.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a scroll type compressor that is a type of a rotary compressor. More particularly, the present invention relates to a structure of the compressor and a method of making the same.

[0002] Japanese Unexamined Patent Publication No. 6-280757 discloses a general scroll type compressor. This scroll type compressor compresses refrigerant gas by reducing the volume of the compression chamber as a movable scroll member orbits with respect to a fixed scroll member. An inlet for introducing the refrigerant gas into the compression chamber is formed through a fixed scroll base plate. A movable scroll base plate is provided with a discharge port and a rood-type discharge valve for discharging compressed refrigerant gas at an innermost compression chamber whose volume is the smallest. The pressurized refrigerant gas discharged from compression chamber via the reed-type discharge valve flows into a motor chamber, and circulates from the motor chamber to an external refrigerant circuit.

[0003] According to the above-mentioned scroll type compressor a shaft sealing member is disposed between a drive shaft driving a movable scroll member and a housing rotatably supporting the drive shaft. Part of the compressed refrigerant gas discharged into the motor chamber tends to leak into a relatively low pressure region through any gap between the drive shaft and a housing. However, the refrigerant gas is inhibited from leaking into the relatively low pressure region by disposing the shaft sealing member between the drive shaft and the housing.

[0004] An unwanted effect of the above-mentioned scroll type compressor is that disposing the shaft scaling member causes to arise friction between the shaft sealing member and the drive shaft, with a consequence of deterioration of efficiency of compression. However, if the shaft scaling member is not disposed between the drive shaft and the housing, the pressurized refrigerant gas tends to leak from the motor chamber to the low pressure region.

SUMMARY OF THE INVENTION

[0005] The present invention addresses the above-mentioned problems traceable to a power loss and a sealing performance of the shaft sealing member disposed between the drive shaft and the housing in the compressor by reducing the power loss and leakage of gas about the shaft sealing member.

[0006] According to the present invention, a scroll type compressor has a housing, a fixed scroll member, a drive shaft, a movable scroll member, an inlet and a discharge device. The fixed scroll member is fixed to the housing. The drive shaft is rotatably supported by the housing. The movable scroll member is accommodated in tho housing, and faces the fixed scroll member. The movable scroll member and the fixed scroll member define a compression region. The inlet is formed through the housing. The discharge device is provided for one of the movable scroll member and the fixed scroll member. Gas introduced into the compressor via the inlet is compressed in the. compression region by orbiting the movable scroll member relative to the fixed scroll member by rotation of the drive shaft. The pressurized gas is discharged via the discharge device. A plane bearing is disposed between the drive shaft and the housing. The plane bearing performs both a bearing function and a shaft sealing function. Based on the bearing function of the plane bearing, the drive shaft smoothly rotates and a power loss due to friction can be reduced, as compared with disposing another shaft sealing member between the drive shaft and the housing. Also, the pressurized gas can be inhibited from leaking into a relatively low pressure region through any gap between the drive shaft and the housing. Besides, the “gas” includes not only refrigerant gas used in a refrigerator and an air conditioner but also various kinds of gas, further including part of gas is solidified. Accordingly, sealing performance of the shaft sealing member can he ensured and the power loss can be reduced by use of the plane bearing.

[0007] The present invention also provides a method of making a scroll type compressor. The method includes the steps of providing a discharge device for one of a movable scroll member and a fixed scroll member, and disposing a plane bearing between a drive shaft and a housing. Accordingly, sealing performance of the shaft scaling member can be ensured and the power loss can be reduced.

[0008] Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The features of the present invention that ARE believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

[0010]FIG. 1 is a longitudinal cross-sectional view of a scroll type compressor according to an embodiment of the present invention; and

[0011]FIG. 2 is a longitudinal cross-sectional partial view of a scroll type compressor providing a discharge device for a fixed scroll base plate according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will now be described with reference to FIG. 1. The present embodiment applied the present invention to a scroll type compressor that compresses refrigerant gas closed in a compression chamber, which is defined between a fixed scroll member and a movable scroll member, and discharges the refrigerant gas compressed therein. FIG. 1 is a longitudinal cross-sectional view of a scroll type compressor according to the embodiment of the present invention. The left side and the right side in FIG. 1 correspond to the front end and the rear end, respectively.

[0013] As shown in FIG. 1, a movable scroll member 20 and its drive mechanism are hermetically accommodated in a housing assembly as a housing of a scroll type compressor 1, and the housing assembly is constituted of a fixed scroll member 2, a center housing 4 and a motor housing 6. The center housing 4 is connected to the fixed scroll member 2 at its front end, and is connected to the motor housing 6 at its rear end. A drive shaft 8 is rotatably supported by both the center housing 4 via a plane bearing 62 (corresponding to a plane bearing in the present invention) and the motor housing 6 via a radial bearing 12. The plane bearing 62 is accommodated in a boss 4 a of the center housing 4. A crankshaft 14 radially offset from the axis of the drive shaft 8 is integrally formed on the front end of the drive shaft 8. A thrust bearing 60 is disposed around the periphery of the front end of the drive shaft 8, and wholly or partially surrounds the drive shaft 8. The thrust bearing 60 can counter thrust force acting on the drive shaft 8 toward the right in FIG. 1, effectively. The center housing 4 provides an annular groove at the front and surface of the center housing 4 facing the rear end surface of a movable scroll base plate. 247 and a seal 80 occupies the groove. The seal 80 at least partially seals any gap between the sliding surface of the center housing 4 and the sliding surface of the movable scroll base plate 24.

[0014] The fixed scroll member 2 has a fixed spiral wall 28 extending from the rear surface of a fixed scroll base plate 26. Likewise, the movable scroll member 20 has a movable spiral wall 30 extending from the front surface of the disk-shaped movable scroll base plate 24. A scroll tip seal 28 a occupies a groove in the end of the fixed spiral wall 28, and a scroll tip seal 30 a occupies a groove in the end of the movable spiral wall 30. The base plate 26 and spiral wall 28 of the fixed scroll member 2 and the base plate 24 and spiral wall 30 of the movable scroll member 20 cooperatively form compression chambers 32 as a compression region because the spiral walls 27, 30 contact at plural points. The compression chambers are sealed spaces, and are falcate. The respective walls 28, 30 of the fixed and movable scroll members 2, 20 are aligned to engage with each other. The movable scroll member 20 orbits in accordance with the rotation of the crankshaft 14, creating traveling points of contact between the two walls 28, 30. As the movable scroll member 20 orbits, the volumes of the compression chambers 32 are progressively reduced, thus compressing the refrigerant gas as gas trapped in the volumes between the spiral walls 28, 30 and discharging the refrigerant gas from a discharge port 50.

[0015] A balance weight 18 cancels centrifugal force generated by the orbital motion of the movable scroll member 20. All orbiting mechanism is constituted of the crankshaft 14, which integrally rotates with the drive shaft 8, a bushing 16, and a plane bearing 22, which is interposed between the crankshaft 14 and a boss 24 a of the movable, scroll member 20. Two mutually parallel planes (a pair of planes) 14 a are formed on a circumferential surface of the crankshaft 14, and the crankshaft 14 is fitted in the bushing 16 so that the bushing 16 can integrally rotate with the crankshaft 14 through the planes. The balance weight, 18 is connected to the rear end of the bushing 16 so as to rotate integrally with the bushing 16, while the movable scroll member 20 is connected to the bushing 16 so as to face the fixed scroll member 2 so that the movable scroll member 20 can relatively rotate with the bushing 16 via the plane bearing 22. Also, the plane bearing 22 is accommodated in a cylindrical boss 24 a extending from the rear surfaces of the base plate 24 of the movable scroll member 20.

[0016] A reed-type discharge valve mechanism 52, which opens and closes the discharge port 50, is affixed to the rear surface of the movable scroll base plate 24 (an opposite surface relative to the crankshaft 14). This discharge valve mechanism 52 has a reed valve 54 disposed at the discharge port 50, a retainer 56 supporting the reed valve 54 and a bolt 58 fixing the reed valve 54 and the retainer 56 to the movable scroll base plate 24, and is accommodated in a discharge valve chamber 25 which is bored at the rear surface of the movable scroll base plate 24. The reed valve 54 opens and closes due to pressure difference between the compression chamber 32 communicated with the discharge port 50 and a high pressure chamber 70. Namely, when the pressure in the compression chamber 32 is higher than the pressure in the high pressure chamber 70, the reed valve 54 opens. When the pressure in the compression chamber 32 is lower than the pressure in the high pressure chamber 70, the reed valve 54 closes. Also, the retainer 56 not only retains the reed valve 54 but also regulates the maximum opening size of the reed valve 54. A discharge device is constituted of the discharge port 50 and the discharge valve mechanism 52.

[0017] A plurality of recesses 41 (e.g. four recesses) is formed on an identical circumference in the front end surface of the center housing 4 in an equiangular positions. Movable pins 40 fixed to the movable scroll base plate 24 are loosely fitted into the associated recesses so that the movable pins 40 can contact with fixed pins 42 fixed to the center housing 4. The recesses 41, the fixed pins 42 and the movable pins 40 prevent the movable scroll member 20 from rotating even if the crankshaft 14 rotates. Namely, a rotation preventing mechanism is constituted of the recesses 41, the fixed pins 42 and the movable pins 40.

[0018] A stator 46 is fixed to an inner circumferential surface of the motor housing 6, and a rotor 48 is fixed to the drive shaft 8. The stator 46 and the rotor 48 constitute the motor. The rotor 48 and the drive shaft 8 integrally rotate by energizing the stator 46. As the crankshaft 14 of the drive shaft 8 rotates, the movable scroll member 20 orbits, and the refrigerant gas is introduced through an inlet 44, which is formed through the fixed scroll member 2, and the refrigerant gas flows from a peripheral side of both the scroll members 2, 20 in between the fixed scroll base plate 26 and thc movable scroll base plate 24. Also, as the movable scroll member 20 orbits, the movable pins 40 slide along the outer circumferential surfaces of the assoiciated fixed pins 42. As the crankshaft 14 rotates, the movable scroll member 20, which can relatively rotate with respect to the crankshaft 14 via the plane bearing 22, orbits about the axis of the drive shaft 8 without itself rotating. As the movable scroll member 20 orbits due to the rotation of the crankshaft 14, the refrigerant gas is introduced through the inlet 44, and is closed in the compression chamber 32. As the compression chamber 32 moves toward the center, the refrigerant gas accordingly is inwardly led to the center of the movable scroll member 20 in parallel with compressing and pressurizing the refrigerant gas. The pressurized refrigerant gas flows into the discharge port 50, which is communicated with the compression chamber 32, the pressure of which is the highest among the compression chambers 32, defined at the center of the movable scroll base plate 24.

[0019] The compressed refrigerant gas passing through the discharge port 50 and the discharge valve mechanism 52 is discharged into the high pressure chamber 70 inside the boss 24 a. This high pressure chamber 70 communicates with the motor chamber 6 a via a first axial passage 72 formed within the drive shaft 8 (including the crankshaft 14), and the. refrigerant gas flowed into the motor chamber 6 a is discharged from a second axial passage 74 formed within the drive shaft 8 to an external refrigerant circuit via an outlet 76, which is formed through a motor housing 6. The motor is cooled by the refrigerant gas while the refrigerant gas is flowing from the first axial passage 72 to the second axial passage 74.

[0020] The plane bearings 22, 62 function not only as a bearing but also as a seal. In other words, the plane bearing 22 functions so as to inhibit the refrigerant gas from leaking from the high pressure chamber 70 into a relatively low pressure region adjacent to the rear surface of the movable scroll base plate 24 via any gap between the bushing 16 and the boss 24 a. Meanwhile, the plane bearing 62 functions so as to rotate the drive shaft 8 smoothly basted on the bearing function, so that the friction generated go between the drive shaft 8 and the center housing 4 and the power loss can be reduced. The plane bearing 62 also functions so as to inhibit the pressurized refrigerant gas in the motor chamber 6 a from leaking into the relatively low pressure region adjacent to the rear surface of the movable scroll base plate 24 via any gap between the drive shaft 8 and the center housing 4. Accordingly, such structure ensures the sealing performance about the drive shaft 8. Moreover, lubricant contained in the refrigerant gas occupies a small gap between the drive shaft 8 and the plane bearing 62. Particularly, the discharge port 50 and the discharge valve mechanism 52 are disposed at the rear surface of the movable scroll base plate 24, and the pressurized refrigerant gas is discharged to the roar surface side of the movable scroll base plate 24, so that the plane bearing disposed at the hearing portion of the drive shaft 8 is efficient.

[0021] Nevertheless, the leakage of the refrigerant gas cannot completely be inhibited. Part of the pressurized refrigerant gas in the high pressure chamber 70 and the motor chamber 6a tends to leak into the relatively low pressure region via the respective plant bearings 22, 62 due to the pressure difference between two regions. However, the seal 80 is disposed so as to restrain the refrigerant gas from leaking into the inlet side. Thereby, an intermediate pressure chamber 78 is defined between the high pressure chamber 70 and a low pressure chamber 19 communicating with the inlet side. Namely, part of the pressurized refrigerant gas in the high pressure chamber 70 and the motor chamber 80 6 a leaks due to the pressure difference, that is, leaks to the intermediate pressure chamber 78, then to the low pressure chamber 79 at the rear surface side of the movable scroll base plate 24.

[0022] Since the seal 80 is disposed downstream to the plane bearings 22, 62, each of which has a seal function, the refrigerant gas can further be inhibited from leaking into the rear surface side of the movable scroll base plate 24, with a consequence of reduced leakage of the refrigerant gas. Also, as the intermediate pressure chamber 78 is defined in the vicinity of the rear surface of the movable scroll hase plate 24, the. force pressing against the movable scroll member 20 increases. Accordingly, the force pressing the movable scroll member 20 against the fixed scroll member 2 increases, with a consequence of reduced leakage of the refrigerant gas from the compression chambers 32

[0023] According to the above-mentioned scroll type compressor 1 and a method for compressing gas, the refrigerant gas in the motor chamber 6 a leaking into the intermediate pressure chamber 78 via the gap between the drive shaft 8 and the center housing 4 can be retrained. Furthermore the seal 80 maintains pressure in the intermediate pressure chamber 78. Therefore, the refrigerant gas leaking from the motor chamber 6 a into the intermediate pressure chamber 78 due to the pressure difference between the front and rear sides of the plane bearing 62 can be minimized

[0024] According to the present embodiment, the drive shaft 8 smoothly rotates due to the bearing function of the plane bearing 62, and the power loss due to the friction generated between the drive shaft 8 and the center housing 4 can be reduced, as compared with disposing another shaft scaling member therebetween. Especially in the present embodiment such that the pressurized refrigerant gas is discharged to the rear surface side of the movable scroll member 20, the plane bearing 62 disposed at the bearing portion of the drive shift 8 is efficient.

[0025] According to the present embodiment, since the discharge port 50 and the discharge valve mechanism 52 are disposed at the movable scroll base plate 24, the passage of the refrigerant gas flowing from the discharge valve mechanism 52 into the motor chamber 6 a can simply be constructed.

[0026] The present invention is not limited to the embodiment described above, but may be modified in the manner set forth in the following examples:

[0027] (A) In the embodiment described above, the thrust bearing 60 receiving the thrust force acting on the drive shaft 8 is disposed on the front end surface of the center housing 4. However, the position of the thrust bearing 60 is not limited to that location, but can variously be modified for other situations. For example, if the thrust force act. on the drive shaft 8 toward the left in FIG. 1, the thrust bearing 60 may be disposed on the rear end surface of the center housing 4 wholly or partially surrounding the drive shaft 8.

[0028] (B) In the embodiment described above, the seal 80 is disposed at the front end surface of the center housing 4 between the movable scroll base plate 24 and the center housing 4. However, the seal 80 may be disposed at the rear end surface of the movable scroll base plate 24.

[0029] (C) In the embodiment described above, the discharge port 50 and the discharge valve mechanism 52 are provided for the, movable scroll member 20. However, the discharge port 50 and the discharge valve mechanism 52 may be provided for the fixed scroll member 2, which is shown in FIG. 2.

[0030] (D) In the embodiment described above, the compressor compresses the refrigerant gas, and pressurizes the refrigerant gas. However, the present invention may be applied to a compressor that compresses gas other than the refrigerant gas.

[0031] The above described scroll type compressor 1 according to the present invention, the sealing performance of the shaft seal of the drive shaft 8 driving the movable scroll member 20 can be ensured and the power loss can be reduced.

[0032] Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims. 

What is claimed is:
 1. A scroll type compressor comprising: a housing; a fixed scroll member fixed to the housing; a drive shaft rotatably supported by the housing; a movable scroll member accommodated in the housing, the movable scroll member facing the fixed scroll member, the movable scroll member and the fixed scroll member defining a compression region; an inlet formed through the housing; a discharge device provided for one of the movable scroll member and the fixed scroll member; wherein gas introduced into the compressor via the inlet is compressed in the compression region by orbiting the movable scroll member relative to the fixed scroll member by rotation of the drive shaft, and the pressurized gas is discharged via the discharge device; and a plane bearing disposed between the drive shaft and the housing to at least partially seal any gap between the drive shaft and the housing against the passage of the pressurized gas therethrough.
 2. The scroll type compressor according to claim 1 further comprising: a thrust bearing between a surface of the drive shaft and the housing wholly or partially surrounding the drive shaft to counter the thrust force acting on the drive shaft.
 3. The scroll typo compressor according to claim 1 further comprising: a seal disposed between the movable scroll member and the housing.
 4. The scroll type compressor according to claim 3, wherein the groove in which the seal resides is recessed on the housing.
 5. The scroll type compressor according to claim 1, wherein the discharge device is provided on the surface of the base plate of thc movable scroll member.
 6. The scroll type compressor according to claim 1, wherein thc discharge device is provided on the surface of the base plate of the fixed scroll member.
 7. A scroll typo compressor comprising: a housing; a fixed scroll member fixed to the housing; a drive shaft rotatably supported by the housing; a movable scroll member accommodated in the housing, the movable scroll member facing the fixed scroll member, the movable scroll member and the fixed scroll member defining a compression region; an inlet formed through the housing; a discharge device provided for one of the movable scroll member and the fixed scroll member; wherein gas introduced into thc compressor via the inlet is compressed in the compression region by orbiting the movable scroll member relative to the fixed scroll member by rotation of the drive shaft, and the prcssurized gas is discharged via the discharge device; and a seal disposed between the movable scroll member and the housing.
 8. The scroll type compressor according to claim 7, wherein the groove in which the seal resides is recessed on the housing.
 9. The scroll type compressor according to claim 7, wherein the discharge device is provided on the surface of the base plate of the movable scroll member.
 10. The scroll typo compressor according to claim 7, wherein the discharge device is provided on the surface of the base plate of the fixed scroll member.
 11. A method of making a scroll type compressor comprising the steps of: providing a discharge device for one of a movable scroll member and a fixed scroll member; and disposing a plane bearing between a drive shaft and a housing.
 12. The method of making a scroll type compressor according to claim 1 1 further comprising the step of disposing a thrust bearing around the drive shaft. 13.The method of making a scroll type compressor according to claim 1 1 further comprising the step of disposing a seal between the movable scroll member and the housing.
 14. The method of making a scroll type compressor according to claim 13 further comprising the step of recessing a groove in which the seal resides on the housing.
 15. The method of making a scroll type compressor according to claim 11 further comprising the stop of providing the discharge device on the surface of the base plate of the movable scroll member.
 16. The method of making a scroll typo compressor according to claim 11 further comprising the step of providing the discharge device on the surface of the base plate of the fixed scroll member. 